Check the control housing screen for contamination
WARNING: This page is about a different car, the 2004 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Checking The Control Housing Screen For Contamination
Courtesy of VOLKSWAGEN UNITED STATES, INC.
Unclip the screen - 2
- from the backside of the control housing - 1
- and remove any contaminants.